Op-amp chips: LM358, LM324, TL072 and LM741
The LM358, LM324, TL072 and LM741 op-amp chips, in their DIP packages with their datasheet pinouts.
The LM358 has two amplifiers (DIP-8), the LM324 four (DIP-14), the TL072 two JFET-input amplifiers (DIP-8), and the LM741, also sold as the uA741 or "IC 741", one (DIP-8). Aliases: LM358N, LM358P, LM324N, TL072CP, uA741, IC741, operational amplifier, comparator.
Every amplifier inside is the same model the op-amp part uses, with the numbers of its datasheet: open-loop gain, a gain-bandwidth product, a slew rate, an output that stops short of its rails, an output resistance and a short-circuit current limit. The amplifiers in one package share its supply pins and nothing else.
Pinouts
Pin 1 is next to the notch, and the numbers run counter-clockwise seen from above: along the bottom row left to right, then back along the top.
| Pin | LM358 | TL072 | LM741 |
|---|---|---|---|
| 1 | 1OUT |
1OUT |
NULL1 (offset null) |
| 2 | 1IN- |
1IN- |
IN- |
| 3 | 1IN+ |
1IN+ |
IN+ |
| 4 | GND |
VCC- |
V- |
| 5 | 2IN+ |
2IN+ |
NULL2 (offset null) |
| 6 | 2IN- |
2IN- |
OUT |
| 7 | 2OUT |
2OUT |
V+ |
| 8 | VCC |
VCC+ |
NC |
The LM324 is a DIP-14: 1OUT, 1IN-, 1IN+, VCC, 2IN+, 2IN-, 2OUT on
pins 1 to 7, then 3OUT, 3IN-, 3IN+, GND, 4IN+, 4IN-, 4OUT on pins 8
to 14. Its supply is on pins 4 and 11, not on the corners.
The numbers
| Chip | open-loop gain | gain-bandwidth | slew rate | output swing | short circuit |
|---|---|---|---|---|---|
| LM358, LM324 | 100 000 | 0.7 MHz | 0.3 V/µs | from 5 mV above GND to 1.5 V under VCC |
40 mA |
| TL072 | 200 000 | 3 MHz | 13 V/µs | 1.5 V inside both rails | 40 mA |
| LM741 | 200 000 | 1 MHz | 0.5 V/µs | 1.5 V inside both rails | 25 mA |
Each output is behind its open-loop output resistance (100 Ω, 75 Ω for the 741), so a load pulls it down a little: an LM358 sitting at its 3.5 V top into 10 k reads 3.47 V.
Properties
offset is the input offset voltage in millivolts, added to every amplifier in
the package, and zero unless you set it. A real chip's offset is a few millivolts
either way and differs from one amplifier to the next; setting it shows what it
does to a comparator's switching point or a high-gain stage's output.
Which one to use
On a single 5 V supply, the LM358 or LM324. Their outputs reach ground, so a
signal near 0 V can be amplified and a comparator's low is a real logic low. They
cannot get closer than 1.5 V to VCC, so on 5 V the output tops out at 3.5 V,
which an Arduino still reads as HIGH.
On a split supply, the 741 or the TL072. Wire V- (or VCC-) to a negative
supply, such as -12 V, and the output can go both sides of ground. On a single
5 V supply both are stuck between 1.5 V and 3.5 V: a 741 asked for 0 V gives
1.5 V. That is why a 741 copied from a textbook onto a 5 V Arduino circuit does
not work, and the simulator shows it.
While it runs
Each output lead and its label light while that output is above the middle of the supply. Put a multimeter or a scope on a pin to read the voltage.
What the model gets right
The non-inverting gain of 1 + Rf / Rg, the inverting gain of -Rf / Rin, the output swing of each chip, its slew rate on the LM358, LM324 and 741 (an LM358 comparator takes about 5 µs to rise 1.5 V), its gain-bandwidth product in an AC sweep, and comparator use with no feedback at all.
What it does not model
The inputs draw no current, so the TL072's JFET inputs, which are what it is
bought for, cannot be told apart from the LM358's. There is no common-mode input
range: a real LM358's inputs stop working within 1.5 V of VCC, and a real 741's
about 3 V from either rail, and here they work anywhere. There is no phase
reversal, no supply current, and the swing does not shrink with load current.
The TL072's 13 V/µs is faster than the simulator draws a slew, so its edges are
set by its 3 MHz bandwidth instead. The 741's offset-null pins and NC are not
connected to anything: a nulling trimmer on them does nothing, so use offset.
Common mistakes
Running a 741 on 5 V and wondering why the output never goes below 1.5 V. Leaving
the second amplifier of an LM358 floating does no harm here, but on a real chip
tie its + input to ground and its output to its - input, so it sits still.
Forgetting the supply: with nothing on VCC or on GND, or with VCC on a rail
nothing powers, the chip has no supply and its outputs drive nothing, so an LED on
one stays dark and a meter reads whatever the load pulls the pin to.
See it in action
LM358 amplifier on a scope, LM358 dark switch with an Arduino, 741 vs LM358 on 5 V, LM324 four-LED bar graph and TL072 amplifier on +-12 V are in the gallery at /templates, and /learn/lm358-op-amp-simulator walks through them.